The invention relates to an auxiliary system for providing positive steering to marine crafts using jet propulsion systems, typically personal jet driven watercrafts such as jet boats and jet skis.
By way of background, there are two types of jet propulsion systems currently in use. The first type most commonly used is found on personal watercrafts usually referred to as Jet Skis. This type uses a directional nozzle. The nozzle turns from side to side directing water from the jet to change the direction of the watercraft.
The second type is commonly used on Jet Boats. This type of system incorporates a movable hood or cover over the directional nozzle to force the water from the jet below the boat to add reverse thrust and allows the boat to back up. For forward thrust, it is pulled up above the jet nozzle.
In both types, the steering of the watercraft relies completely on the direction and force of the water being expelled from the directional nozzle. This steering method is extremely unreliable as it responds slowly and fails totally if power is reduced or turned off. As a result, there have been many deadly accidents as a result of such watercraft not being able to quickly and positively respond to a need for directional change at any speed, even if engine power is cut off.
The present invention addresses this steering deficiency currently found in existing watercrafts powered by jet propulsion systems by incorporating an auxiliary keel system to dramatically enhance the steering performance of such watercrafts. In normal operation, the keel steering enhances the watercraft""s maneuverability with immediate and controlled response.
In operating conditions where the operator reduces the jet power or stalls the engine, the keel steering takes over and the watercraft will steer accurately. Consequently, the present invention makes the operation of jet propelled watercrafts more enjoyable and, more importantly, much safer.
Although the present invention is more fully described hereinafter, in general, the present invention includes, among other features, a combination of keel members attached to a stern section of a hull. The keels are interconnected using tie rods to the directional steering drive assembly. In other embodiments, the keels are instead attached directly to the directional nozzle or incorporated into the manufacture of the directional nozzle as one piece, and where a hood is included in the directional nozzle assembly, notches are included in the keels to allow for full operation of the hood into its lowest position. For the latter embodiments, although one center keel will work, a divergently depending two keel system or a two keel system together with a center keel further enhance the watercraft steering performance.
For safety purposes, the bottom edges of the keels are preferably rounded off with a radius of at least {fraction (3/16)} inch. This feature can also be included by gradually tapering the keels to widen at the bottom edges to accommodate the rounded bottoms.
In addition, in circumstances where the keel member are designed to be part of the directional nozzle, then the tapered keel may be hollow such that a portion of the outlet flow of water can also be directed through the hollow portion of the keel members and exit the back edge of the keel members in a substantially parallel direction to the general flow of the water out the directional nozzle.
If more positive reaction to steering is desired or even less positive reaction to steering is desired, than the contemplated 1:1 response in the embodiment using tie rods described below, an odd number of apertures, linearly arranged where the tie rod ends are connected together could be provided so that an owner can adjust the sensitivity of the steering response by connecting the tie rod ends to the central aperture for 1:1 response, to an aperture closer to the stern for a little less rapid and lesser response (less than 1:1) and to an aperture further away for a more rapid and greater response (greater than 1:1).
In still another embodiment of the invention, two more keel members can be incorporated into a directional nozzle with a ridge being formed along either side of the directional nozzle so as to form cupped sides between each outside keel member and the ridges. It is also preferred, but not necessary, that a cup be formed on the directional nozzle between the keel members as well. Where the outside keel members depend relatively straight down from the directional nozzle, it is recommended that the most bottom ends of each outside keel member (when two or three keel members are included) be formed to bow or slightly bend outwardly.